Embossing filter

http://archive.gamedev.net/archive/reference/programming/features/imageproc/page2.html

 

 

Algorithm 9 : Embossing effect filter

• Convert the image into grayscale
• For every pixel ( i , j ) on the output bitmap
• Compute its color using formula (R13)
• Set the pixel

#define emboss_w 3
#define emboss_h 3    

sumr=0;
sumg=0;
sumb=0;
    
int emboss_filter[emboss_w][emboss_h]={{2,0,0},{0,-1,0},{0,0,-1}};
int emboss_sum=1;
 
for(i=1;i<temp->w-1;i++){
  for(j=1;j<temp->h-1;j++){
    color=getpixel(temp,i,j);
    r=getr32(color);
    g=getg32(color);
    b=getb32(color);
    h=(r+g+b)/3;
    if(h>255)
      h=255;
    if(h<0)
      h=0;
    putpixel(temp1,i,j,makecol(h,h,h));
  } 
} 

for(i=1;i<temp->w-1;i++){
  for(j=1;j<temp->h-1;j++){
    sumr=0;
    for(k=0;k<emboss_w;k++){
      for(l=0;l<emboss_h;l++){
        color=getpixel(temp1,i-((emboss_w-1)>>1)+k,j-((
        emboss_h-1)>>1)+l);
        r=getr32(color);
        sumr+=r*emboss_filter[k][l];
      }
    }
    sumr/=emboss_sum;
    sumr+=128;
    if(sumr>255)
      sumr=255;
    if(sumr<0)
      sumr=0;
    putpixel(temp2,i,j,makecol(sumr,sumr,sumr));
  }
}

Here are the effects of this algorithm:

Picture 9: Embossing filter